The government is contemplating raising the school-leaving age to 18 to combat unemployment, according to the Guardian. The idea "tops" a list drawn up by Gordon Brown's advisers and would mean speeding along a plan that was to have been left for five years. As a cure for unemployment it is economically illiterate – any short-term check on the labour supply would be countered by the longer-term economic damage. Why not go the whole way and follow the old Soviet model and have everyone employed by the state and thus eliminate unemployment at a stroke? (Even if the jobs were often the broad equivalents of digging holes in the ground and then filling them in again.)

Tony Benn once declared that he would raise the school-leaving age to 95. I think he was joking. To attempt to deal with the economic slowdown by shrinking the potential workforce is a counsel of despair. Just as with proposals to force people to retire early. It is a fallacy that there is a fixed amount of work available. A zero sum game. But by going out and working and earning money and generating wealth we contribute to economic growth.

But that is not the only, or even the main concern. Forget the economics. What about the educational impact? The last time the school-leaving age was raised was in 1972 to the age of 16, the education secretary at the time was Margaret Thatcher. She certainly seems to have been proud of the change. In her pre-prime ministerial memoirs The Path to Power she wrote: "I fought hard to have an unqualified commitment to raising the school-leaving age included in our manifesto, and succeeded against some doubts from the Treasury team." She added later, once it had been introduced: "I pushed through the raising of the school-leaving age which the Labour party had had to postpone."

But what did those thousands of hours of compulsory schooling achieve? Lower unemployment? Unemployment in 1971 was 725,000. Switzerland and Estonia do pretty well with a school-leaving of 15. Higher educational standards? We have 45,000 children leaving school each year unable to read.

One curiosity about this initiative is that it coincides with Gordon Brown's support for lowering the voting age to 16. Those judged too young to be allowed to leave school will still be old enough to decide who runs the country. At least it would be give disaffected school pupils an outlet for their frustration.

A positive alternative would be to lower the school-leaving age back down to 14 but with the important provisos that children are allowed to leave at this age only if they can pass an exam proving that they have achieved basic standards of literacy and numeracy. This would have a transformational effect. For children to be bored does not mean that they are stupid. The more bored a child is to be stuck at school, the greater the incentive to pass the exam. At Pimlico School, the comprehensive I attended, we used to call truancy "bunking off". The teachers were secretly pleased when the bored children "bunked off" because the alternative was them attending the lessons and disrupting them. Increasing the school-leaving age will not result in more being learned – just more broken windows in the locality of the school. Children fed up with school need an escape route, not an extension of their sentence.

Another important proviso for being allowed to leave school at 14 should be that those without a job lined up agree to take up an apprenticeship. The government says it wants to boost apprenticeships but so far has given no sign of this being much more than a gimmick. A target is announced and then forgotten; Sir Alex Ferguson, the Manchester United manager, Sir Alan Sugar, the businessman, and Gary Rhodes, the chef, have been "enlisted" to support the idea. We need sufficient tax breaks to make employers regard it as worth their while to take the youngsters on. It would help if employers knew that those who wanted to join them had been motivated to pass an exam to leave school early so that they could get into the world of work.